Difference between revisions of "MOVING REFERENCE MODELS"
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The fixed-reference models rely on an abstract coordinate, which is arbitrarily defined and unfortunately has no morphogenetic or physiological meaning. Chambers (circles or spheres) are rotated and translated along these artificial axes, which are fixed and serve as a reference line for the growth process. Therefore, while these models can simulate simple planispiral, trochospiral or uniserial chamber arrangement, they cannot simulate more complex patterns found in foraminifera. For instance, they cannot model gradual or abrupt changes of growth modes that cause different chamber arrangements during ontogeny, such as planispiral and switching to biserial or streptospiral to uniserial. CITED AFTER [[OUR PUBLICATIONS|Tyszka & Topa, 2005]]. | The fixed-reference models rely on an abstract coordinate, which is arbitrarily defined and unfortunately has no morphogenetic or physiological meaning. Chambers (circles or spheres) are rotated and translated along these artificial axes, which are fixed and serve as a reference line for the growth process. Therefore, while these models can simulate simple planispiral, trochospiral or uniserial chamber arrangement, they cannot simulate more complex patterns found in foraminifera. For instance, they cannot model gradual or abrupt changes of growth modes that cause different chamber arrangements during ontogeny, such as planispiral and switching to biserial or streptospiral to uniserial. CITED AFTER [[OUR PUBLICATIONS|Tyszka & Topa, 2005]]. | ||
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| + | == Moving-reference models == | ||
[[Image:Reference1mov.jpg|thumb|right|222px| <font size="2">'''The moving-reference model reffers to a coordinate frame, which moves in every step of the model.''']] | [[Image:Reference1mov.jpg|thumb|right|222px| <font size="2">'''The moving-reference model reffers to a coordinate frame, which moves in every step of the model.''']] | ||
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These constraints can be overcome by abandoning a fixed-reference frame in favor of a moving-reference system. In general, the moving reference model is based on simple principles of motion and stepwise growth. At each growth step, the aperture migrates to a new position, according to locally defined rules (Ackerly 1989). Such models have been employed in simulating ammonite growth. Okamoto (1988) proposed a tube model for all types of shell coiling, including heteromorph forms with abrupt changes of coiling patterns. His approach integrates accretional growth of the aperture (opening of the shell) without defining any fixed coordinate system. A similar moving-reference frame has been used in simulating radiate accretive growth of marine sessile organisms, such as corals and sponges, where the growth axis is associated with the local maximum of growth (e.g., Kaandorp 1994; Hammer, 1998; Kaandorp and Kuebler 2001). A comparable approach was used in simulating plant growth (Lindenmayer 1968; Prusinkiewicz and Lindenmayer 1990). CITED AFTER [[OUR PUBLICATIONS|Tyszka & Topa, 2005]]. | These constraints can be overcome by abandoning a fixed-reference frame in favor of a moving-reference system. In general, the moving reference model is based on simple principles of motion and stepwise growth. At each growth step, the aperture migrates to a new position, according to locally defined rules (Ackerly 1989). Such models have been employed in simulating ammonite growth. Okamoto (1988) proposed a tube model for all types of shell coiling, including heteromorph forms with abrupt changes of coiling patterns. His approach integrates accretional growth of the aperture (opening of the shell) without defining any fixed coordinate system. A similar moving-reference frame has been used in simulating radiate accretive growth of marine sessile organisms, such as corals and sponges, where the growth axis is associated with the local maximum of growth (e.g., Kaandorp 1994; Hammer, 1998; Kaandorp and Kuebler 2001). A comparable approach was used in simulating plant growth (Lindenmayer 1968; Prusinkiewicz and Lindenmayer 1990). CITED AFTER [[OUR PUBLICATIONS|Tyszka & Topa, 2005]]. | ||
